The present invention relates to the field of network management in data communications networks.
Network management systems are used to monitor and control the operational behavior of data communications networks and the individual devices included in such networks. Operational characteristics of networks and devices can be monitored to obtain information useful to a network management user such as a network administrator. Such characteristics can include, for example, the manner in which various devices are connected to each other, the capacities and relative utilization of communications links among the devices, the extent and locations of faults or problems in the network such as traffic congestion and packet loss, etc. On the control side, network management systems are utilized to configure the network devices in accordance with a plan of network operation, for example by defining virtual circuits used to carry traffic between devices, and establishing forwarding tables and filtering rules that are used in routing and selective filtering of traffic.
For network management systems to be effective, it is important that they contain accurate information regarding the operational state of the managed devices. Information can be maintained in the network management system based on explicit monitoring of the devices, or based on a combination of monitoring and inferences drawn from control operations. That is, if the network management system is used to configure a network device, the network management can infer that the device's operational configuration is that which would normally result from the stream of configuration commands sent to the device from the network management system. By such operation, the amount of explicit monitoring or polling of a network device to obtain configuration information can be reduced. However, there may be circumstances under which it is desirable to explicitly obtain configuration information from a managed device in order to ensure that device information in the network management system is accurate. Therefore, there is a need for efficient and robust mechanisms by which such information transfers can be accomplished.